1. Field of the Invention
The present invention relates generally to a prosthetic hearing implant and, more particularly, to independently and concurrently processes multiple audio input signals in a prosthetic hearing implant.
2. Related Art
There are a variety of medical implants which deliver electrical stimulation to a patient or recipient (“recipient” herein) for a variety of therapeutic benefits. For example, the hair cells of the cochlea of a normal healthy ear convert acoustic signals into nerve impulses. People who are profoundly deaf due to the absence or destruction of cochlea hair cells are unable to derive suitable benefit from conventional hearing aid systems. Prosthetic hearing implants have been developed to provide such persons with the ability to perceive sound. Prosthetic hearing implants bypass the hair cells in the cochlea to directly deliver electrical stimulation to auditory nerve fibers, thereby allowing the brain to perceive a hearing sensation that resembles the natural hearing sensation.
The electrodes implemented in stimulating medical implants vary according to the device and tissue which is to be stimulated. For example, the cochlea is tonotopically mapped and partitioned into regions, with each region being responsive to stimulus signals in a particular frequency range. To accommodate this property of the cochlea, prosthetic hearing implant systems typically include an array of electrodes each constructed and arranged to deliver appropriate stimulating signals to particular regions of the cochlea, each representing a different frequency component of a received audio signal.
Currently, most prosthetic hearing implant recipients have difficulty understanding speech in a noisy environment. With the moderate signal-to-noise ratios which are somewhat tolerable by normal hearing listeners, such as zero to five decibels (dB), speech reception by hearing implant recipients is dramatically reduced. Considering that only limited speech information is available through the hearing implant, this reduction in capability is, to a certain degree, unavoidable.
Noise and speech sources are often spatially separated. The ability of normal hearing individuals to differentiate between multiple distinct sources of sound is often due in part to the listener's ability to use spatial hearing to distinguish between multiple sound sources. In contrast, conventional prosthetic hearing implants intermingle or combine multiple sound signals into a single audio signal which is presented to the cochlear. As a result, hearing implant recipients are unable to differentiate between two or more different streams of auditory input. For example, in contrast to a hearing implant recipient, normal hearing listeners are typically able to participate in a conversation with a person in their immediate vicinity while simultaneously hearing background music.